Ignition mechanism for engines



March 12, 1940. .1. L. DOLL Er AL IGNITION MECHANISM FOR ENGINES 3nventor John L. D011 Clifford W Po erns Original Filed July 6, 1937 k Gttorneg Patented Mar. 12, 1940 IGNITION MECHANISM FOR ENGINES John L. Doll and Clifiord W. Rogers, Detroit,

Mich., assignors to Syncro Devices, Incorporated, Detroit, Mich, a corporation of Michigan Original application July 6, 1937, Serial No.

152,036. Divided and this application November 28, 1938, Serial N0. 242,791 v 11 Claims.

This invention relates to internal combustion engines and particularlyignition mechanisms for such engines, and the present application is diil gsignal to our application #152,036, filed July 6,

An object of the invention is to provide an ignition mechanism, particularly applicable to a light, compact, high-speed engine, designed for relatively light loads.

Another object is to so assemble the crank shaft of an internal combustion engine, a head in which such shaft is journaled, and a make-and-break device for the ignition circuit, that the assembly may be conveniently attached to and detached from an engine as a unit.

A further object is to provide an improved and highly simplified make-and-break device for the ignition circuit, and to so mount and position such device as to safeguard it from dirt, grease and oil.

A further object is to provide a pair of contacts for making and breaking the engine ignition circuit, and to mount one thereof on a lever or arm periodically rocked by an engine-driven element, such arm being operatively disposed in relation to the driven element by a member carrying the other contact.

A further object is to install said contacts on a collar adapted for angular adjustment to ad-' Vance or retard the spark, and to mount one of the contacts on a member projecting from the collar and forming-a handle for adjusting the latter.

These and various other objects are attained by the construction hereinafter described and illustrated in the accompanying drawing wherein:

Fig. 1 is a front end view of an engine equipped with the improved ignition mechanism.

Fig. 2 is a view in side elevation of the front end portion of the engine.

Fig. 3 is an enlarged vertical sectional elevation of the front portion of the engine, particularly showing its timing mechanism.

Fig. 4 is a cross section taken on the line 4-4 of Fig. 3.

Fig. 5 is a cross section taken on the line 5-5 of Fig. 4.

In these Views, the reference character I designates the cylinder of an internal combustion engine, 2 a spark plug on the headed upper end of the cylinder, 3 a crank case surmounted by the 8 pressed into a circular head 9 closing the front end of the crank case andsecured thereto by screws I 0. I p

The head 8 is formed axially with a tubular outward extension H, interiorly accommodating the outer portion of the bearing 8 and exteriorly carrying a collar l2, which mounts the ignition circuit make-and-break device. Said collar is split (preferably at its bottom), as indicated at I3, adapting it to be clamped onthe extension It so as to maintain a desired rotative position. Said collar is sufficiently free, however, to afford it a rotative adjustment for spark advancement or re: tardation, as more fully hereafter explained. Peripherally opening in said collar, diametrically opposite to the split 4 3, is a rectangular pocket I4, into which is set a fibre or other insulating support l5 having a reduced upward extension carrying a contact point it. This support is securely clamped in the pocket by a screw l1 and is sufi'lciently spaced from the bottom and a circumferentialwall of the pocket to accommodate a bell crank lever l8, l9 and afford the'latter a PTENT. err-res slight rocking movement, as best appears in Fig. 3. I

The arm [8 projects upwardly between the support l5 and said circumferential wall and carries a contact point 20 p'ositioned'to engage the'point I6. The arm IQ of the bell crank'lever extends between the support l5 and the bottom of the with the cam 2|, the latter being fashioned to establish and maintain contact during the required cycle interval. The pocket walls engaged by the screw H are preferably adapted for such slight flexure aswill permit clamping of the support 15 between such walls. ,By rotatively adjusting' the collar l2, the make-and-break device is angularly shifted with respect to the cam 21,

to advance or retard the spark.

The disclosed engine may have a variety of uses, but is particularly suited, by reason of .its light weight and compact form, to driving the propeller of a model aeroplane. Thus, there is shown a propeller 23 clamped on the forward portion of the shaft 4 between collars 24, a nut 25 being threaded-on the shaft extremity for applying the clamping pressure. It is preferred, in employing such collars, to form the cam 2i integrally with one known two-cycle principle, the cam 22! thereof, as best appears in Fig. 3, the collar l 2 be ing recessed to accommodate the cam.

The described engine operates on the wellbeing hence effective to close the ignition circuit during a portion of each crank shaft revolution.

The crankshaft 4, collar l2, and described parts carried by such shaft and collar may be assembled as a unit and then mounted in operative relation to the crank case by means of the screws Ill. The bottom face of the support l5 and the rear face of its lower portion meet at an acute angle, as Fig. 3 clearly discloses, forming an edge which engages the bell-crank lever at the Juneture of its arms l8 and I9 and fulcrums such lever. By employing the support 15 to operatively position the bell-crank lever, additionally to mount the contact 24, and further as a handle for effecting angular adjustment of the collar 12, the construction is simplified and the number of assembly operations is minimized.

The invention is presented as including all such modifications and changes as come within the scope of the following claims.

What we claim is:

1. In an internal combustion engine, a makeand-break device comprising a driven shaft, a cam fixed on such shaft, a pair of coacting con.- tact points, a non-conducting fixed support for one of the contact points, a bell crank lever having an arm outwardly-projecting from the shaft and carrying the other contact point and having an arm extending between the non-conducting support and shaft and terminally bearing on the cam, and a spring acting on the bell crank lever maintaining its engagement with the cam and resisting disengagement of the contact points.

2. In an internal combustion engine, a makeand-break device as set forth in claim 1, the nonconducting support retaining the bell crank lever in operative position.

3. In an internal combustion engine as set forth in claim 1, a carrier for the make-andbreak device, having a pocket in which the nonconducting support is fixed, the bell crank lever being operatively positioned on the carrier by extending its cam-engaging arm between the bottom of the pocket and said support and by extending its contact-carrying arm outwardly between a wall of the pocket and said support.

4. In an internal combustion engine as set forth in claim 1, a carrier for the make-andbreak device, having a pocket in which the nonconducting support is fixed, the bell crank lever being operatively positioned on the carrier by extending its cam-engaging arm between the bottom of the pocket and said support and by extending its contact-carrying arm outwardly between a wall of the pocket and said support, said spring reacting between the contact-carrying arm and said wall of the pocket.

5. In an internal combustion engine, a makeand-break device comprising a mounting, a pair of coacting contact points, one movable to engage and disengage the other, and individual supports for said points, the support for the movable point being pivotally positioned on said mounting by the support for the other point.

6. In an internal combustion engine, a makeand-break device comprising a mounting, a pair of coacting contact points, one movable to engage and disengage the other, and individual supports for said points, the mounting having a pocket to receive said supports, and the support for the movable point being operatively retained in said pocket by the support for the other point.

7. In an internal combustion engine as set forth in claim 6, a shaft extending through said mounting, a cam fixed on and driven by such shaft and acting on the support for the movable contact point to effect periodic engagement of the contacts, said supports having portions projecting exteriorly of said pocket to carry the contacts, Wherebythe latter are readily accessible.

8. In an internal combustion engine, a make and break device comprising a shaft, a cam fixed on and driven by said shaft, a support adjacent to the cam through which support said shaft extends, a split collar substantially coaxial with said shaft and rotative on said support to advance or retard the spark, means engaging said collar at its split for regulating its frictional grip on the support, whereby the collar may be frictionally retained in a selective angular relation'to said support, and a pair of contacts mounted on the collar, one thereof being periodically movable by the cam to engage the other.

9. In an internal combustion engine, a make and break device comprising a shaft, a cam fixed on and driven by such shaft, a bell crank lever pivoted for actuation about an axis substantially transverse to said shaft and actuable through one of its arms by the cam, and a pair of contacts periodically engageable by said lever, one of said pair being carried by the other arm of said bell crank. r

10. In an internal combustion engine, a makeand-break device comprising a driven shaft, a cam fixed on such shaft, a collar angularly adjustable substantially about the shaft axis, a rocker arm carried by such collar, riding on the cam and periodically movable by the cam to open and close the ignition circuit of the engine, and a member carried by the collar, operatively mounting said rocker arm on the collar and maintaining its engagement with the cam and projecting from the collar to form a handle for effecting angular adjustment of the collar.

11. In an internal combustion engine, a makeand-break device comprising a driven shaft, a

cam fixed on such shaft, a collar angularly adjustable substantially about the shaft axis, a member projecting from the collar and forming a handle for angularly adjusting the collar, a contact point carried by such handle member, a coacting contact point, and a member pivotally actuable by said cam about an axis substantially transverse to the shaft for periodically moving the last-mentioned contact point to engage and disengage the first-mentioned contact point.

JOHN L. DOLL. CLIFFORD W. ROGERS. 

